xi MURIATIC ACID AND CHLORINE 227 



redness, a body precisely the same as a dry muriate is 

 formed, and oxygen is expelled from the earth. I have 

 never been able to effect so complete a decomposition of 

 these earths by [chlorine], as to ascertain the quantity of 

 oxygen produced from a given quantity of earth. But in 

 three experiments made with great care I found that one of 

 oxygen was evolved for every two in volume of [chlorine] 

 gas absorbed" (A.C.R. IX. 47). 



The displacement of oxygen by chlorine is effected even 

 more easily by the action of muriatic acid gas or hydrogen 

 chloride. This gas being a HYDRIDE, i.e. a compound of 

 hydrogen with another element, interacts with metallic 

 oxides to form muriates or chlorides and water, thus : 



LITHARGE + MURIATIC ACID GAS -> MURIATE OF LEAD + WATER 

 (Lead + ( Hydrogen + (Lead + chlor- ( Hydrogen + 



oxygen) chlorine) ine) oxygen) 



Under similar conditions an acidic OXIDE, such as fixed 

 air or sulphuric anhydride, unites with the metallic oxide to 

 form a ternary salt and nothing else. 



Berthollet (1788) prepares chlorate of potash. 

 Although the muriates, like the sulphides, were found to be 

 binary compounds containing no oxygen, oxidised muriates 

 (ternary compounds analogous with the sulphates) were 

 discovered at an early date. The most important of these, 

 now known as CHLORATE OF POTASH or POTASSIUM CHLORATE, 

 was first prepared in a pure state by Berthollet in 1788, by 

 passing chlorine gas into hot aqueous potash. (Journ. de 

 Physique, 1788, 33, 217-224). After crystallising out a 

 great deal of muriate of potash (potassium chloride) the new 

 salt was obtained in hexagonal plates with a lustre like 

 mica. These did not taste like muriate of potash, but 

 produced in the mouth " a feeling of freshness closely 

 resembling that of nitre." The salt detonated with char- 

 coal ; after the detonation nothing was left but ordinary 

 muriate of potash the salt was therefore an " oxygenated 



Q 2 



